HD Project to SD finish

[Andy Mees]

However, is there really no way to have compressor or final cut just crop and downconvert in a digital format?

There certainly is. Send your HD edit to Compressor as per normal and then apply an appropriate SD target setting for your output file from the Settings > Apple > Other Workflows > Advanced Format Conversions > Standard Definition presets. Next you need to look at that applied setting in the Inspector window and switch to the Geometry tab and change the “Source Inset (Cropping)” >> Crop to: popup to 4×3 1.33:1.

Hope it helps
Andy